Process for the manufacture of chloroform

ABSTRACT

A process for the manufacture of chloroform by catalytic hydrogenolysis of carbon tetrachloride in liquid phase, wherein liquid phase carbon tetrachloride is reacted with hydrogen gas or a gas containing molecular hydrogen, at a pressure below 8,000 kPa and at a temperature below 250° C., in the presence of a catalyst formed by a metal selected from the group consisting of palladium, rhodium, ruthenium and platinum, deposited on a substrate and held in suspension in the liquid.

BACKGROUND OF THE INVENTION

This invention relates to a process for the preparation of chloroform(CHCl₃), starting out from carbon tetrachloride (CCl₄)

There are references in the literature concerning several methods forreducing the halogen content of a range of organohalogenated compounds.Nevertheless, the majority are impractical and of no commercial interestbecause of their excessive sophistication.

As a result of the declining market for carbon tetrachloride, there is agrowing excess of this product. In view of this situation, researchersare trying to revalue this product by searching for methods allowing itto be used as a raw material for the manufacture of chloroform, themarket demand for which is, on the contrary, growing.

Thus, the Dow Chemical Co. U.S. Pat. No. 2,886,605 of 1959 teaches amethod of hydrodehalogenation of polyhalogenated hydrocarbons, using acuprous chloride catalyst in a fluidized bed. The greatest drawback ofthis method for commercial exploitation is that it is run at so hightemperatures (350° C. to 550° C.) that such an abundant carbonizationoccurs that it becomes necessary continuously or very frequently toregenerate the catalyst.

Another Dow Chemical Co. patent (U.S. Pat. No. 3,579,596 of 1971)teaches a process for producing chloroform from gas phase carbontetrachloride, using a fixed catalyst bed of platinum on a substrate.This method, nevertheless, suffers from serious limitations, forexample, that

a) the need to use excessively high amount of hydrogen relative to astoichiometric amount encourages the production of methane and,furthermore, extraordinarily hinders the recovery of the reactionproducts, and

b) The reaction is highly exothermic (ΔH=-22.70 kcal/ mol, at 400 K, fora 100% theoretical selectivity of chloroform production), making it veryhard to control the temperature. According to trials carried out by theinventors, hot spots are formed in the catalyst in the gas phaseprocess, encouraging the formation of free radicals which, in turn, giverise to the formation of heavy polychlorinated compounds. When these aredeposited on the catalyst surface they almost immediately andirreversibly deactivate it.

SUMMARY OF THE INVENTION

According to the present invention, liquid carbon tetrachloride isreacted with hydrogen gas or with a molecular hydrogen-containing gas,at a pressure below 8,000 kPa and at a temperature below 250° C. in thepresence of a catalyst comprising a metal deposited on a powderedsubstrate. The metal is palladium, rhodium, ruthenium or platinum. Thereaction takes place with the catalyst in suspension in the liquid.

According to the invention, the reaction is conducted in liquid phase,with a supported powdered metal catalyst in suspension in contact withthe molecular hydrogen. The catalyst active component is a metalselected from the group formed by palladium, rhodium, ruthenium andplatinum. Thus, under the conditions to be described hereinafter, thecarbon tetrachloride is converted into chloroform, at low temperature,with high conversion and selectivity rates.

The process has proved to be particularly effective when the chosenmetal is palladium.

The present inventors have discovered, and this is a very importantadvantage of this invention, that when the reaction is conducted underthe abovementioned conditions, the drawbacks mentioned above areavoided.

A further important advantage of the process of the invention is that itallows the temperature to be easily controlled, thereby avoiding theformation of chlorinated polymers and it also allows the activity of thecatalyst to be maintained for sufficient time to make the processcommercially profitable.

Yet a further important advantage of the process of the invention overother known processes, is that the liquid phase system allows a lowexcess of hydrogen to be used, representing an undeniable financialsaving. Furthermore, under these conditions, the production of methaneand other unprofitable by-products is avoided, this being yet a furtheradvantage of the new process.

The catalyst used in the process of the invention is formed by a metalselected from the group formed by palladium, rhodium, ruthenium andplatinum deposited on a suitable substrate, such as carbon, silica,alumina, etc. Thus, a catalyst having shown itself to have a highactivity and selectivity together with high stability is metallicpalladium deposited on activated carbon having a large surface area.

To prepare the catalyst, the metal may be deposited on the substrate byany of the methods regularly used for this purpose, such as, forexample, impregnation with or without an excess of solution,precipitation, etc, using aqueous or organic solvents.

As precursor salts of the metal, chlorides, ammoniacal chlorides,organic complexes, nitrates, acetates, etc. may be used, both in thecommercial form thereof and as a result of dissolving the metal in anappropriate solvent.

Once the precursor has been deposited on the substrate, it is allowed todry at room temperature for three hours and subsequently at atemperature ranging from 100° C. to 140° C. for the time required toremove the residual water.

Thereafter the catalyst is reduced to the metallic state in the presenceof a molecular hydrogen-containing gas or an appropriate reducing gassuch as hydrazine, methane, etc. To improve the activity, the reductionmay be effected at temperatures ranging from 100° C. to 500° C.,preferably from 150° C. to 450° C., the range of 200° C. to 300° C.being most advantageous when the metal is palladium. The reduction maybe effected at atmospheric pressure or at a higher pressure. The optimumduration ranges from 1 to 4 hours and the hydrogen flow from 200 to1,000 liters/hour per kg of catalyst, although an amount of hydrogenranging from 2 to 5 times the amount required to reduce all the metal issufficient.

The metal content of the catalyst may range from 0.1 to 5 wt % relativeto the total weight of the final catalyst, although the preferred rangeis from 0.1 to 2 wt %.

For the very nature of the process of the invention, a high solid-liquidcontact area is required, whereby it is desirable to use the catalyst inpowder form, with a particle size not above 0.45 mm and preferably ofless than 0.2 mm.

Also, to achieve an effective gas-solid-liquid contact and to obtain amaximum performance, it is necessary to remove the physical obstacles tothe diffusion of the hydrogen in the gas-liquid and liquid-solidinterfaces and to establish a control system of the chemical kinetics.Thus, any conventional mechanical stirring system may be used, oradvantage may be taken of the linear velocity of the hydrogen itself,adequately dispersed in the liquid, to create the necessary turbulence.

For the preparation of the catalyst, the substrate may initially havethe form of pellets, grains or extrudates, to be subsequently reduced tothe selected particle size. Nevertheless, the metal precursor may alsobe incorporated directly on the powdered substrate.

To summarize, as said above, this new process of manufacturingchloroform by catalytic hydrogenolysis of carbon tetrachloride ischaracterized essentially in being conducted in the liquid phase,containing the appropriate amount of powdered catalyst in suspension, inthe presence of hydrogen at an appropriate temperature and pressure.

OPERATING CONDITIONS OF THE PROCESS OF THE INVENTION

The process may be operated indifferently batchwise, semi-continuouslyor continuously. For batchwise production, a stirred autoclave typereactor may be used, containing the liquid carbon tetrachloride andcatalyst charge, in the appropriate proportions. Hydrogen is allowed toflow in up to the set pressure, the mass is heated up to the operatingtemperature and is held under these conditions for the time required toachieve the desired conversion. At the end of this time, the reactionproducts are discharged and separated. Both the unreacted reactant andthe catalyst may be reused.

If it is wished to conduct the reaction on a semi-continuous basis,either an autoclave type reactor or a tubular reactor may be used. Theliquid and the catalyst are charged in the required proportions and therequired hydrogen flow is provided. At the same time, the workingtemperature and pressure are adjusted. If the process is carried out ina laboratory, the gaseous effluent of the reactor, containing H₂,hydrogen chloride, methane and chlorinated hydrocarbons, is fed througha water absorption column where the hydrogen chloride is retained.Thereafter, the chlorinated products are condensed at a desirabletemperature and the main reaction product, i.e. the chloroform isseparated from them, for example, by distillation. If necessary, the gasflow and the unreacted reactant may be recycled. The apparatus isprovided with a cyclone and/or filter to recover any entrained catalystand return it to the reactor. The observed losses of catalyst areminimal. Once the desired conversion has been attained, the reactorcontent, after removal of the catalyst, is sent to distillation torecover the chloroform. The unreacted carbon tetrachloride is recycledto the reactor.

The process may be carried out equally well reversing the orderdescribed above for the chlorinated product condensation and thehydrogen chloride absorption. This last operating method is moreappropriate for application in an industrial plant.

When operating continuously, the same operating method is used as in theabove described semi-continuous method, except that in this case thecarbon tetrachloride is also supplied continuously in liquid phase atthe required flow rate. The two reactor effluents, gas and liquid, areseparated and processed as in the previously described semi-continuousoperation.

The high activity shown by the catalyst used in the process of theinvention, together with the reaction being carried out in the liquidphase, not only allows low temperatures to be used, but also anexcellent control of the temperature within the reactor to bemaintained, the gradients not normally exceeding the values of ΔT=±5° C.Thus, hot spots are eliminated, the life of the catalyst is extended andhigh selectivity rates are obtained for the preparation of the desiredproducts. As said above, this is one of the great advantages of theinvention and a notable improvement over the processes carrying out thesame reaction but in the gas phase. Thus, the reaction may be carriedout with satisfactory yields at temperatures ranging from 100° C. to300° C., although temperatures ranging from 120° C. to 160° C. arepreferable.

The reaction is conducted advantageously at pressures above atmosphericpressure. Excessively high pressure do not provide substantialadvantages to the reaction kinetics and increase the production costs.Therefore, the operating pressure should range from 500 to 8,000 kPa andpreferably from 1,500 to 5,000 kPa.

The hydrogen supply should be sufficiently selective to product thedesired reaction, i.e., the preparation of chloroform. This reaction is:

    CCl.sub.4 +H.sub.2 →CHCl.sub.3 +HCl

It is essential that the reaction should not be controlled by theavailability of the hydrogen in the liquid phase, or by the desorptionof the hydrogen chloride produced, which is guaranteed by maintainingalways a slight excess of hydrogen in the gas exhaust and goodmechanical stirring. This excess must, obviously, be higher if thehydrogen flow is also used as stirring system for the liquid and thecatalyst in the reactor. Tests have shown that even using this method ofstirring in a semi-continuous reactor, an H₂ /CCl₄ molar ratio of lessthan 2/1 is sufficient to obtain molar conversions of carbontetrachloride of over 85% and chloroform preparation selectivity ratesof about the same order, after a period ranging from 2 to 4 hoursoperation, depending on the experimental conditions. This low hydrogenconsumption is another important financial incentive of the process ofthe present invention, not provided by other known processes.

Another parameter determining the commercial profitability of thisprocess is the relatively low content of metal used as active component,both in the catalyst composition and in the catalyst/chlorinatedreactant (wt/wt) ratio used in the reactor. For low values of thisratio, the productivity increases more than linearly on increasing it,since thereby the amount of catalyst particles in the slurry and,therefore, the contact area of the catalyst, also increase. It is wellknown that the reaction rate is proportional to this area. Nevertheless,higher values, competition occurs for the H₂ among the catalystparticles, whereby there is a reduction of the effective amount ofcatalyst, saturation is reached and the activity per gram practically nolonger increases. When the catalyst element is palladium, ratios rangingfrom 0.1/100 and 5/100 (wt/wt), more preferably 0.5/100 to 2.5/100, havebeen found to be acceptable for the catalyst/CCl₄ ratio. The highestrates of chloroform production, expressed as kg CHCl₃ /hour per kgpalladium are obtained with these ratios.

EXAMPLES

The following Examples, given without any limitative effect, serve toprovide a better understanding of the invention.

EXAMPLE 1

This Example relates to a way of preparing a palladium catalyst, usingactivated carbon of 1,200 m² /g as substrate, in the form of pellets ofabout 3 mm diameter by 4 mm long. The retention volume or maximum waterabsorption volume is 95 cm³ /g.

1.0 g of powered palladium metal was dissolved in 7.0 ml of aqua regiaat 80° C. Once dissolved, it was dried and the residue was dissolved in5.0 cm³ of 12N hydrochloric acid, at room temperature. The resultingsolution was topped up to 95 cm³ with distilled water and poured over100 g of carbon pellets.

The pellets were thoroughly stirred to produce a homogenous absorptionof the solution, it was allowed to dry at room temperature for threehours and then at 120° C. for twelve hours. Subsequently, it was reducedat 250° C. at atmospheric pressure, with 500 1/hour hydrogen per kgcatalyst being blown over for three hours. It was allowed to cool toroom temperature under hydrogen flow. The catalyst contained 1 wt % ofpalladium metal.

Subsequently, for use in the liquid phase reaction, the catalyst pelletswere reduced to a size of below 0.177 mm.

EXAMPLE 2

This Example relates to the preparation of chloroform (CHCl₃). 2,072 gof liquid carbon tetrachloride were charged into a stainless steeltubular reactor, 1.25 m high×4 cm inside diameter, without mechanicalstirring, and 24.89 g of catalyst prepared as per Example 1 were added.After purging the air, the hydrogen flow was opened and was adjusted togive permanently 1 1/min H₂ in the exhaust. The hydrogen was fed inthrough the bottom of the reactor, was diffused through a perforatedplate and, further to being used as reactant, it was also used to stirthe liquid and the solid. The reactor was heated to 160° C. and thepressure was adjusted to 3,000 kPa. After one hour (t=1 hour) an 86.6%carbon tetrachloride conversion to chloroform, with a 77.6% molarselectivity (S) was obtained, representing a productivity rate (P) of2,762 kg CHCl₃ /hour per kg palladium.

The selectivity (S) is defined as the number of moles of carbontetrachloride converted into product, divided by the total number ofmoles of carbon tetrachloride reacted multiplied by 100.

The main by-products obtained were:

hexachloroethane, with selectivity: S(C₂ Cl₆)=1.2%.

tetrachloroethylene, with selectivity: S(C₂ Cl₄)=14.8%

methane, with selectivity: S(CH₄)=3.9%.

The complements to 100 of the sum of the selectivities of carbontetrachloride and the above main by-products correspond to small amountsof other by-products, such as ethane, trichloroethane, pentachloroethaneand traces of others.

EXAMPLE 3

In an experiment conducted with the same catalyst, the samecatalyst/carbon tetrachloride ratio and the same hydrogen flow in theexhaust and protocol as described in Example 2, but at 140° C. and 1,500kPa, the following results were obtained:

    ______________________________________                                        After 2 hours operation (t = 2 hours)                                         Conversion (CCl.sub.4) = 42.9%                                                S (CHCl.sub.3) = 73.9%                                                        P (CHCl.sub.3) = 1,024 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 18.0%                                                  S (C.sub.2 Cl.sub.4) = 2.6%                                                   S (CH.sub.4) = 0.7%                                                           After 4 hours operation (t = 4 hours)                                         Conversion (CCl.sub.4) = 68.2%                                                S (CHCl.sub.3) = 69%                                                          P (CHCl.sub.3) = 761 kg/hour per kg palladium                                 S (C.sub.2 Cl.sub.6) = 21.0%                                                  S (C.sub.2 Cl.sub.4) = 4.8%                                                   S (CH.sub.4) = 1.8%                                                           ______________________________________                                    

EXAMPLE 4

2,072 g of liquid CCl₄ and 24.86 g of a catalyst prepared according toExample 1, but containing 0.5% wt palladium were charged in the reactordescribed in Example 2. When operating at 140° C. and 1,500 kPa, with 1./min H₂ in the exhaust, the following results were obtained:

    ______________________________________                                        t = 2 hours                                                                   Conversion (CCl.sub.4) = 34.6%                                                S (CHCl.sub.3) = 78.5%                                                        P (CHCl.sub.3) = 1,785 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 13.3%                                                  S (CH.sub.4) = 3.2%                                                           t = 4 hours                                                                   Conversion (CCl.sub.4) = 69%                                                  S CHCl.sub.3) = 74.9%                                                         P (CHCl.sub.3) = 1,671 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 16.5%                                                  S (C.sub.2 Cl.sub.4) = 3.0%                                                   S (CH.sub.4) = 2.9%                                                           ______________________________________                                    

EXAMPLE 5

In an experiment conducted under the same conditions as in Example 4,but containing 51.8 g of catalyst, i.e. a catalyst/CCl₄ ratio of 2.5/100(wt/wt), the following results were obtained:

    ______________________________________                                        t = 2 hours                                                                   Conversion (CCl.sub.4) = 78.1%                                                S (CHCl.sub.3) = 85.9%                                                        P (CHCl.sub.3) = 2,083 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 8.1%                                                   S (C.sub.2 Cl.sub.4) = 3.2%                                                   S (CH.sub.4) = 1.0%                                                           t = 4 hours                                                                   Conversion (CCl.sub.4) = 99.9%                                                S (CHCl.sub.3) = 88.0%                                                        P (CHCl.sub.3) = 1,366 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 0.3%                                                   S (C.sub.2 Cl.sub.4) = 6.5%                                                   S (CH.sub.4) = 1.7%                                                           ______________________________________                                    

EXAMPLE 6

Following the method of Example 1, a palladium catalyst containing 1 wt% of metal was prepared, using as substrate a different activated carbonhaving a specific area of 820 m³ /g and 78% retaining volume.

EXAMPLE 7

An experiment was conducted with the catalyst prepared as per Example 6with the same equipment as in the previous Examples and under the sameexperimental conditions as in Example 3, the following results beingobtained:

    ______________________________________                                        t = 2 hours                                                                   Conversion (CCl.sub.4) = 39.4%                                                S (CHCl.sub.3) = 80.8%                                                        P (CHCl.sub.3) = 1,028 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 9.5%                                                   S (C.sub.2 Cl.sub.4) = 1.0%                                                   S (CH.sub.4) = 3.1%                                                           t = 4 hours                                                                   Conversion (CCl.sub.4) = 72.3%                                                S (CHCl.sub.3) = 77%                                                          P (CHCl.sub.3) = 901 kg/hour per kg palladium                                 S (C.sub.2 Cl.sub.6) = 8.0%                                                   S (C.sub.2 Cl.sub.4) = 2.2%                                                   S (CH.sub.4) = 3.2%                                                           ______________________________________                                    

EXAMPLE 8

An experiment was conducted with a catalyst prepared according toExample 6, but containing 0.5 wt % palladium, semi-continuously, in amechanically stirred reactor, at 140° C. temperature, 1,500 kPapressure, with a catalyst/carbon tetrachloride ratio of 1.2/100 (wt/wt)and a hydrogen flow at the exhaust of 1 l/min. The following resultswere obtained:

    ______________________________________                                        t = 2 hours                                                                   Conversion (CCl.sub.4) = 58.1%                                                S (CHCl.sub.3) = 76.4%                                                        P (CHCl.sub.3) = 2,871 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 16.3%                                                  S (C.sub.2 Cl.sub.4) = 2.9%                                                   S (CH.sub.4) = 3.6%                                                           t = 4 hours                                                                   Conversion (CCl.sub.4) = 94.8%                                                S (CHCl.sub.3) = 79.6%                                                        P (CHCl.sub.3) = 2,441 kg/hour per kg palladium                               S (C.sub.2 Cl.sub.6) = 7.0%                                                   S (C.sub.2 Cl.sub.4) = 9.6%                                                   S (CH.sub.4) = 3.1%                                                           ______________________________________                                    

EXAMPLE 9

This Example relates to a way of preparing a rhodium (Rh) catalyst.

A rhodium (Rh) catalyst was prepared by dissolving in distilled waterthe amount of rhodium trichloride (RhCl₃) necessary for the finalcatalyst to contain 1.6 wt % of rhodium metal relative to the totalcatalyst weight. Distilled water was added to the resulting solution tocomplete a volume equal to the retention volume of the carbon used inExample 1. After impregnating the substrate with this solution, it wasdried at 120° C. for twelve hours and was then reduced at 150° C., underflowing hydrogen, for two hours.

EXAMPLE 10

An experiment was conducted with the catalyst prepared according toExample 9 under the same conditions as described in Example 8, but usinga catalyst/carbon tetrachloride ratio of 1.0/100 (wt/wt). The followingresults were obtained:

    ______________________________________                                        t = 2 hours                                                                   ______________________________________                                        Conversion (CCl.sub.4) = 4.8%                                                 S (CHCl.sub.3) = 32.0%                                                        P (CHCl.sub.3) = 37.7 kg/hour per kg rhodium                                  S (C.sub.2 Cl.sub.6) = 61.6%                                                  S (C.sub.2 Cl.sub.4) = 6.1%                                                   S (CH.sub.4) = Traces                                                         ______________________________________                                    

EXAMPLE 11

This Example relates to a way of preparing a ruthenium (Ru) catalyst.

A catalyst containing 1.6 wt % of ruthenium (Ru) was prepared fromruthenium trichloride (RuCl₃, using the same method and substrate as inExample 9, except that the reduction was conducted at 250° C.

EXAMPLE 12

An experiment was conducted with the catalyst described in Example 11,under the same conditions as Example 10, with the following resultsbeing obtained:

    ______________________________________                                        t = 2 hours                                                                   ______________________________________                                        Conversion (CCl.sub.4) = 10%                                                  S (CHCl.sub.3) = 9%                                                           P (CHCl.sub.3) = 20.7 kg/hour per kg ruthenium                                S (C.sub.2 Cl.sub.6) = 86.0%                                                  S (C.sub.2 Cl.sub.4) = 3.0%                                                   S (CH.sub.4) = 2.0%                                                           ______________________________________                                    

EXAMPLE 13

This Example relates to a way of preparing a platinum (Pt) catalyst.

A platinum catalyst was prepared using powdered silica of 600 m² /gspecific area and 3.0 cm³ /g specific retention volume as substrate. 1 gof hexachloroplatinic acid (H₂ PtCl₆.6H₂ O) was dissolved in distilledwater to complete a volume of 113 cm³. The solution was poured over 37.5g of substrate. Once the solid was well impregnated, it was dried at120° C. for 12 hours, was calcined at 500° C. under flowing air for twohours and was reduced at 450° C. under flowing hydrogen for two hours.The final catalyst contained 1 wt % of platinum metal.

EXAMPLE 14

An experiment was conducted with the catalyst prepared according toExample 13 under the same conditions as described in Example 8, with thefollowing results being obtained:

    ______________________________________                                        t = 2 hours                                                                   ______________________________________                                        Conversion (CCl.sub.4) = 2.1%                                                 S (CHCl.sub.3) = 30%                                                          P (CHCl.sub.3) = 17.5 kg/hour per kg platinum                                 S (C.sub.2 Cl.sub.6) = 70%                                                    S (CH.sub.4) = 0%                                                             ______________________________________                                    

EXAMPLE 15

Example 15 also deals with the preparation of a platinum catalyst.

Following the method of Example 13, a platinum catalyst was prepared,but using the activated carbon of Example 6. After impregnation anddrying, the catalyst was reduced directly with H₂ at 450° C., withoutprior calcination. The final catalyst contained 1 wt % of platinummetal.

EXAMPLE 16

An experiment was conducted with the catalyst of Example 15, under theconditions described in Example 8, with the following results beingobtained:

    ______________________________________                                        t = 1 hour                                                                    ______________________________________                                        Conversion (CCl.sub.4) = 61.5%                                                S (CHCl.sub.3) = 75.3%                                                        P (CHCl.sub.3) = 2,992 kg/hour per kg platinum                                S (C.sub.2 Cl.sub.6) = 16.4%                                                  S (C.sub.2 Cl.sub.4) = 6.2%                                                   S (CH.sub.4) = 2.0%                                                           ______________________________________                                    

The results given in the foregoing Examples show that the process of theinvention is sufficiently versatile to be adaptable to variousindustrial situations. In fact, by varying the operative conditions,different combinations of carbon tetrachloride conversion and chloroformproductivity rates may be obtained, in all cases with a relatively smallamount of by-products. In each case, an analysis of the differentoperating power, separation and recycling costs, together with the rawmaterial and product market prices, will allow the most profitableproduction scheme to be adopted.

We claim:
 1. A process for manufacture of chloroform by catalytichydrogenolysis of carbon tetrachloride, comprising the steps of reactingliquid carbon tetrachloride with a hydrogen-containing member selectedfrom the group consisting of hydrogen gas and gases containing molecularhydrogen at a pressure below 8,000 kPa and at a temperature below 250°C., in the presence of a catalyst, said catalyst comprising a metaldeposited on a powdered substrate, and said catalyst being held insuspension in the liquid carbon tetrachloride, said metal being selectedfrom the group consisting of palladium, rhodium, ruthenium and platinum.2. The process according to claim 1, wherein the powdered substrate isselected from the group consisting of activated carbon, silica andalumina powders.
 3. The process according to claim 1, further comprisingimpregnating the substrate with a solution of at least one slat of themetal selected as active component of the catalyst.
 4. The processaccording to claim 3, wherein the salt is selected from the groupconsisting of inorganic salts and organic salts.
 5. The processaccording to claim 3, wherein the solution is an organic solution. 6.The process according to claim 3, wherein the solution is an aqueoussolution.
 7. The process according to claim 1, further comprisingprecipitating a precursor substance containing the metal selected asactive component of the catalyst onto the substrate.
 8. The processaccording to claim 1, wherein said reacting is conducted batchwise witha charge of liquid carbon tetrachloride containing the catalyst insuspension, and further comprising supplying said hydrogen-containingmember up to a working pressure.
 9. The process according to claim 1,wherein said reacting is conducted semi-continuously with a charge ofliquid carbon tetrachloride containing the catalyst in suspension, andfurther comprising supplying said hydrogen-containing member up to aworking pressure.
 10. The process according to claim 1, wherein saidreacting is conducted continuously with the liquid carbon tetrachlorideand the hydrogen-containing member being supplied continuously, andfurther comprising suspending the catalyst in the liquid carbontetrachloride.
 11. The process according to claim 1, further comprisingstirring the liquid carbon tetrachloride mechanically.
 12. The processaccording to claim 1, further comprising stirring the liquid carbontetrachloride by action of a flow of the hydrogen-containing member. 13.The process according to claim 1, wherein the reacting occurs in one ofan autoclave and a tubular reactor.
 14. A process for manufacture ofchloroform by catalytic hydrogenolysis of carbon tetrachloride,comprising the steps of reacting liquid carbon tetrachloride with ahydrogen-containing member selected from the group consisting ofhydrogen gas and gases containing molecular hydrogen at a pressure below8,000 kPa and at a temperature below 250° C., in the presence of acatalyst, said catalyst comprising a metal deposited on a powderedsubstrate, and said catalyst being held in suspension in the liquidcarbon tetrachloride, said metal being selected from the groupconsisting of palladium, rhodium, ruthenium and platinum, and whereinthe catalyst and the liquid carbon tetrachloride are present in a weightratio of from 0.1/100 to 5/100 during the reacting.
 15. The processaccording to claim 14, wherein the weight ratio is from 0.5/100 to2.5/100.
 16. The process according to claim 1, wherein thehydrogen-containing member and the liquid carbon tetrachloride arepresent in a weight ratio of one to two times a stoichiometric ratio fora reaction of the hydrogen-containing member with the carbontetrachloride.
 17. A process for manufacture of chloroform by catalytichydrogenolysis of carbon tetrachloride, comprising the steps of reactingliquid carbon tetrachloride with a hydrogen-containing member selectedform the group consisting of hydrogen gas and gases containing molecularhydrogen at a pressure below 8,000 kPa and at a temperature below 250°C., in the presence of a catalyst, said catalyst comprising a metaldeposited on a powdered substrate, and said catalyst being held insuspension in the liquid carbon tetrachloride, said metal being selectedfrom the group consisting of palladium, rhodium, ruthenium and platinum,and wherein the temperature during said reacting is from 100 C. to below250° C.
 18. The process according to claim 17, wherein the temperatureduring said reacting is from 120° C. to 160° C.
 19. A process formanufacture of chloroform by catalytic hydrogenolysis of carbontetrachloride, comprising the steps of reacting liquid carbontetrachloride with a hydrogen-containing member selected from the groupconsisting of hydrogen gas and gases containing molecular hydrogen at apressure below 8,000 kPa and at a temperature below 250° C., in thepresence of a catalyst, said catalyst comprising a metal deposited on apowdered substrate, and said catalyst being held in suspension in theliquid carbon tetrachloride, said metal being selected from the groupconsisting of palladium, rhodium, ruthenium and platinum, and whereinthe pressure during the reacting is from 500 kPa to below 8,000 kPa. 20.The process according to claim 19, wherein the pressure during thereacting is from 1,500 kPa to 5,000 kPa.
 21. A process for manufactureof chloroform by catalytic hydrogenolysis of carbon tetrachloride,comprising the steps of reacting liquid carbon tetrachloride with ahydrogen-containing member selected from the group consisting ofhydrogen gas and gases containing molecular hydrogen at a pressure below8,000 kPa and at a temperature below 250° C., in the presence of acatalyst, said catalyst comprising palladium deposited on a powderedsubstrate, and said catalyst being held in suspension in the liquidcarbon tetrachloride.
 22. The process according to claim 21, furthercomprising dissolving the palladium in a solvent to form a palladiumsalt and impregnating the substrate with the palladium salt.
 23. Theprocess according to claim 22, wherein the palladium salt is one of aninorganic palladium salt and an organic palladium salt.
 24. The processaccording to claim 21, wherein the catalyst contains from 0.1 to 5.0% byweight of the palladium relative to a total catalyst weight.
 25. Theprocess according to claim 21, wherein the catalyst contains from 0.1 to2.0% by weight of the palladium relative to a total catalyst weight. 26.The process according to claim 22, further comprising reducing thepalladium salt to palladium metal with hydrogen gas at a temperatureranging from 100° C. to 500°.
 27. The process according to claim 26,wherein the temperature of said reducing is from 200° C. to 300° C. 28.The process according to claim 1, wherein the metal is the rhodium. 29.The process according to claim 1, wherein the metal is the ruthenium.30. The process according to claim 1, wherein the metal is the platinum.31. A process for manufacture of chloroform by catalytic hydrogenolysisof carbon tetrachloride, comprising the steps of:a) impregnating apowdered substrate with at least one palladium salt by treating thepowdered substrate with the at least one palladium salt in a solvent; b)reducing the at least one palladium salt impregnated on the powderedsubstrate to form a catalyst containing palladium metal, said reducingbeing carried out with hydrogen gas at a temperature ranging from 100°C. to 500° C. so that the catalyst contains from 0.10 to 5.0% by weightof the palladium metal; and c) reacting liquid carbon tetrachloride witha hydrogen-containing member selected from the group consisting ofhydrogen gas and gases containing molecular hydrogen at a pressure from500 to below 8,000 kPa and at a temperature from 100° C. to below 250°C. in the presence of the catalyst to form the chloroform, wherein thecatalyst and the liquid carbon tetrachloride are present in a weightratio of 0.1/100 to 5/100 during the reacting.